Just heart wrenching. And not that the other souls onboard were any less important, but one of the passengers was a widow of someone killed 9/11 going to Buffalo to celebrate her dead husbands birthday. Yikes.
Early supposition is ice buildup as the aircraft descended towards the airport. Eyewitnesses also reported the engines making sputtering sounds.
The aircraft was about 5 miles out and 2300' which puts it over the outer marker. They would have been fully configured by that point. I suppose a stall if their angle of attack was increased due to ice accumulation is also a possibility.
Regardless of reasons, my heart goes out to those effected by this.